It depends on where you are planning to go in the southeast. Florida would be very different than the Smokies for example.
For Clothes
Temps ~60* highs while hiking ~40* lows at night
In the Daytime:
Short Sleeve Mountain Hardwear Wicked Tee
REI Sierra Convertible Pants
Nightime:
Patagonia Capaline 1 Long Sleeve Shirt
REI Sierra Convertible Pants
Mont-Bell Thermawrap
Temps ~50* highs while hiking ~30* lows at night
Daytime:
Smartwool Lightweight 1/4 Zip Long Sleeve Shirt
REI Sierra Convertible Pants
Nightime:
Patagonia Capaline 1 Long Sleeve Shirt
Patagonia Capaline 1 Pants
REI Sierra Convertible Pants
Mont-Bell Thermawrap
Temps ~40* highs while hiking ~20* lows at night
Daytime:
Smartwool Lightweight Long Sleeve Crew
REI Sierra Convertible Pants
O R lightweight beanie (if needed)
100wt fleece gloves (if needed)
Marmot Ion widshirt (if needed)
Nighttime:
Patagonia Capaline 1 Long Sleeve Shirt
Patagonia Capaline 1 Pants
REI Sierra Convertible Pants
Patagonia Micro Puff Pullover
O R 300wt fleece mittens
Mountain Hardwear Windproof Fleece Hat
Sierra Designs Down Booties
Temps ~30* highs while hiking single digit lows at night
Daytime:
Ibex Norgie Mid weight Long Sleeve Crew
REI Sierra Convertible Pants
O R lightweight beanie (if needed)
100wt fleece gloves (if needed)
Marmot Ion windshirt (if needed)
Nighttime:
Patagonia Capaline 1 Long Sleeve Shirt
Patagonia R1 Pants
REI Sierra Convertible Pants
Patagonia R1 Flash Pullover
Patagonia Micro Puff Pullover
O R 300wt fleece mittens
Mountain Hardwear Windproof Fleece Hat
Campmor Fleece Neck Gaiter
Sierra Designs Down Booties
Note: I also carry rain gear (Golite Phantom Jacket and Marmot Precip Pants) and add them in camp if extra warmth is needed.
I also have 3 sleeping bags
Western Mountaineering Summerlite 32*
Western Mountaineering Ultralite 20*
Mountain Hardwear Phantom 0*
and three sleeping pads
Thermarest Z-lite
Thermarest Prolite 3
Exped Downmat 7
Depending on where you are going your Caraboiu might not be enough. I was at Mt. Rogers (Southwest VA) in the middle of August and it was 38* , and Mt. LeConte in the smokies has already had several nights in the 30's. I have seen snow as early as October and as late as May in the higher elevations.